arm64/ptrace: Preserve previous registers for short regset write

Ensure that if userspace supplies insufficient data to
PTRACE_SETREGSET to fill all the registers, the thread's old
registers are preserved.

Cc: <stable@vger.kernel.org> # 3.19.x-
Fixes: 766a85d7bc ("arm64: ptrace: add NT_ARM_SYSTEM_CALL regset")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <Will.Deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Dave Martin 2017-01-18 16:25:21 +00:00 committed by Catalin Marinas
parent 9a17b876b5
commit 9dd73f72f2
1 changed files with 2 additions and 1 deletions

View File

@ -677,7 +677,8 @@ static int system_call_set(struct task_struct *target,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
int syscallno, ret;
int syscallno = task_pt_regs(target)->syscallno;
int ret;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &syscallno, 0, -1);
if (ret)